<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgl - Multiple Render Targets</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">

		<!-- Write to G-Buffer -->
		<script id="gbuffer-vert" type="x-shader/x-vertex">
			in vec3 position;
			in vec3 normal;
			in vec2 uv;

			out vec3 vNormal;
			out vec2 vUv;

			uniform mat4 modelViewMatrix;
			uniform mat4 projectionMatrix;
			uniform mat3 normalMatrix;

			void main() {

				vUv = uv;

				// get smooth normals
				vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );

				vec3 transformedNormal = normalMatrix * normal;
				vNormal = normalize( transformedNormal );

				gl_Position = projectionMatrix * mvPosition;

			}
		</script>
		<script id="gbuffer-frag" type="x-shader/x-fragment">
			precision highp float;
			precision highp int;

			layout(location = 0) out vec4 gColor;
			layout(location = 1) out vec4 gNormal;

			uniform sampler2D tDiffuse;
			uniform vec2 repeat;

			in vec3 vNormal;
			in vec2 vUv;

			void main() {

				// write color to G-Buffer
				gColor = texture( tDiffuse, vUv * repeat );

				// write normals to G-Buffer
				gNormal = vec4( normalize( vNormal ), 0.0 );

			}
		</script>

		<!-- Read G-Buffer and render to screen -->
		<script id="render-vert" type="x-shader/x-vertex">
			in vec3 position;
			in vec2 uv;

			out vec2 vUv;

			uniform mat4 modelViewMatrix;
			uniform mat4 projectionMatrix;

			void main() {

				vUv = uv;
				gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

			}
		</script>
		<script id="render-frag" type="x-shader/x-fragment">
			precision highp float;
			precision highp int;

			layout(location = 0) out vec4 pc_FragColor;

			in vec2 vUv;

			uniform sampler2D tDiffuse;
			uniform sampler2D tNormal;

			void main() {

				vec3 diffuse = texture( tDiffuse, vUv ).rgb;
				vec3 normal = texture( tNormal, vUv ).rgb;

				pc_FragColor.rgb = mix( diffuse, normal, step( 0.5, vUv.x ) );
				pc_FragColor.a = 1.0;

			}
		</script>

	</head>
	<body>
		<div id="info">
			<a href="http://threejs.org" target="_blank">threejs</a> - WebGL - Multiple Render Targets<br/>
			Renders geometry into a G-Buffer.<br/>
			Visualized here is the color and normal data from the G-Buffer.<br/>
			Created by <a href="http://twitter.com/mattdesl" target="_blank">@mattdesl</a>.
		</div>

		<script type="module">

			import * as THREE from '../build/three.module.js';

			import { WEBGL } from './jsm/WebGL.js';
			import { OrbitControls } from './jsm/controls/OrbitControls.js';

			let camera, scene, renderer, controls;
			let renderTarget;
			let postScene, postCamera;

			init();

			function init() {

				if ( WEBGL.isWebGL2Available() === false ) {

					document.body.appendChild( WEBGL.getWebGL2ErrorMessage() );
					return;

				}

				renderer = new THREE.WebGLRenderer();
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				document.body.appendChild( renderer.domElement );

				// Create a multi render target with Float buffers

				renderTarget = new THREE.WebGLMultipleRenderTargets(
					window.innerWidth * window.devicePixelRatio,
					window.innerHeight * window.devicePixelRatio,
					2
				);

				for ( let i = 0, il = renderTarget.texture.length; i < il; i ++ ) {

					renderTarget.texture[ i ].minFilter = THREE.NearestFilter;
					renderTarget.texture[ i ].magFilter = THREE.NearestFilter;
					renderTarget.texture[ i ].type = THREE.FloatType;

				}

				// Name our G-Buffer attachments for debugging

				renderTarget.texture[ 0 ].name = 'diffuse';
				renderTarget.texture[ 1 ].name = 'normal';

				// Scene setup

				scene = new THREE.Scene();

				camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 1, 10 );
				camera.position.z = 4;

				const diffuse = new THREE.TextureLoader().load(

					'textures/brick_diffuse.jpg',

					function () {

						// ready to render
						render();

					}

				);

				diffuse.wrapS = diffuse.wrapT = THREE.RepeatWrapping;

				scene.add( new THREE.Mesh(
					new THREE.TorusKnotGeometry( 1, 0.3, 128, 64 ),
					new THREE.RawShaderMaterial( {
						vertexShader: document.querySelector( '#gbuffer-vert' ).textContent.trim(),
						fragmentShader: document.querySelector( '#gbuffer-frag' ).textContent.trim(),
						uniforms: {
							tDiffuse: { value: diffuse },
							repeat: { value: new THREE.Vector2( 5, 0.5 ) }
						},
						glslVersion: THREE.GLSL3
					} )
				) );

				// PostProcessing setup

				postScene = new THREE.Scene();
				postCamera = new THREE.OrthographicCamera( - 1, 1, 1, - 1, 0, 1 );

				postScene.add( new THREE.Mesh(
					new THREE.PlaneGeometry( 2, 2 ),
					new THREE.RawShaderMaterial( {
						vertexShader: document.querySelector( '#render-vert' ).textContent.trim(),
						fragmentShader: document.querySelector( '#render-frag' ).textContent.trim(),
						uniforms: {
							tDiffuse: { value: renderTarget.texture[ 0 ] },
							tNormal: { value: renderTarget.texture[ 1 ] },
						},
						glslVersion: THREE.GLSL3
					} )
				) );

				// Controls

				controls = new OrbitControls( camera, renderer.domElement );
				controls.addEventListener( 'change', render );
				controls.enableZoom = false;
				controls.screenSpacePanning = true;

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

				const dpr = renderer.getPixelRatio();
				renderTarget.setSize( window.innerWidth * dpr, window.innerHeight * dpr );

				render();

			}

			function render() {

				// render scene into target
				renderer.setRenderTarget( renderTarget );
				renderer.render( scene, camera );

				// render post FX
				renderer.setRenderTarget( null );
				renderer.render( postScene, postCamera );

			}

		</script>

	</body>
</html>
